Cell motility is a key fundamental process in development, immunity, and metastasis of cancers. Until recently, most studies have focused on the biochemical characterization of these phenomena. However, mechanical cues from the extracellular matrix play an important role in the regulation of cell locomotion. We propose to measure cell migration mechanics as a function of force by developing a fluorescent force sensor molecule. Based on a DNA hairpin structure, the molecule has a modular design with the well characterized duplex of the hairpin serves as the force sensing component, while a FRET pair at the base of the hairpin serves as a reporter of the force necessary to unzip the hairpin. We have calibrated the molecule and measured the simultaneous conformational and fluorescence transitions occur at 18 pN. To study cellular adhesion forces at the molecular level, we have incorporated an RGD-containing adhesion peptide, common to the extracellular matrix protein, fibronectin, for integrin-mediated adhesion to the sensor. In preliminary results, we have validated the chemistry for synthesis of the force sensor molecule on a coverslip. We will image where adhesive force is applied to the matrix by a loss of intramolecular FRET with a conventional fluorescence microscope. Because the force information is visual, we will non-computationally generate a dynamic 'molecular force map'of a motile cell. Because of its simplicity and lack for computation, the force visualization technology has the potential to be a basis for force-based assays by cell biologists who lack expertise in sophisticated mechanics, computational, or optics. Public Health Relevance: Cell migration is a fundamental process in the development of embryonic tissues and organs, the maintenance of adult tissues, and the transition to metastasis in cancer. A large gap in our understanding of migration is the origin and magnitude of cellular forces that characterize the mechanics of movement. A molecular fluorescent force sensor would provide the capability of detecting and reporting molecular forces in situ and thus map out the force fields generated when a cell moves through a 3D matrix of tissue fibers.